1. Field of the Invention
The present invention relates to a method and an apparatus for rinsing various substrates, for example, silicon wafers, glass substrates, electronic components (hereinafter simply referred to as substrates) in heated deionized water and drying the surface thereof in a manufacturing process that is used to produce semiconductor devices, liquid crystal display and other electronic components.
2. Description of the Related Art
In a process of manufacturing semiconductor devices, liquid crystal displays, electronic components or the like, contamination of a substrate by foreign particles must be eliminated. Thus, the step of rinsing and drying the substrate and an apparatus thereof is very important in a process of manufacturing semiconductor devices and the like.
A method and an apparatus for rinsing various substrates, such as silicon wafers, with heated water and drying the surface of the substrates after rinsing thereof is disclosed in Japanese Patent Laying-Open No. 3-30330.
Referring to FIG. 1, the conventional apparatus includes a chamber 202 in which the steps of rinsing and drying are carried out.
The chamber 202 includes an outer chamber 204 shielded by a lid 208, and an inner chamber 206 provided in the outer chamber 204 and having an opening in the upper portion.
The outer chamber 204 has a supply inlet 210 for nitrogen gas formed on the upper side surface. A flow line 220 is connected to the supply inlet 210 for nitrogen gas. An open/close valve 222 is provided in the flow line 220. The end of the flow line 220 is connected to a supply source for nitrogen gas, not shown.
An exhaust outlet 214 for exhausting air in the chamber 202 is formed at the bottom portion of the outer chamber 204. An exhaust flow line 218 is connected to the exhaust outlet 214.
The exhaust flow line 218 includes a flow line 234 having one end connected to the exhaust outlet 214, and an exhaust open/close valve 246 provided in the flow line 234. The other end of the flow line 234 is connected to a vacuum pump 236.
A water inlet/outlet 212 is provided at the bottom portion of the inner chamber 206. A water supply and discharge flow line 216 is connected to the water inlet/outlet 212.
The water supply and discharge flow line 216 includes a flow line 224 having one end connected to the water inlet/outlet 212, flow lines 226 and 228 branching from the flow line 224, and flow lines 230 and 232 further branching from the flow line 226. The flow lines 230 and 232 are connected to supply sources (not shown) for heated deionized water and deionized water, respectively. A water discharge open/close valve 238, a water supply open/close valve 240, heated water open/close valve 242, and water open/close valve 244 are provided in the flow lines 228, 226, 230, and 232, respectively. The other end of the flow line 228 is connected to the aforementioned vacuum pump 236.
A substrate is rinsed and dried as in the following with this apparatus. First, a plurality of substrates W are prepared which are carried in a carrier C. The carrier C is housed in the inner chamber 206.
Heated water is poured into the inner chamber 206 through the flow lines 230, 226, 224, and the water inlet/outlet 212, and the substrates are dipped therein. Then the pressure in the chamber 202 is reduced to the vapor pressure of the heated water or less with the vacuum pump 236, causing the heated water to boil. The substrates W are rinsed by the boiling of the heated water under the reduced pressure.
After rinsing the substrates W, deionized water is poured into the inner chamber 206 through the flow lines 232, 226, 224, and the water inlet/outlet 212, causing the substrates W to be rinsed in the deionized water to be clean. At this time, the deionized water overflowing from the inner chamber 206 is discharged outside the outer chamber 204 through the exhaust outlet 214.
Then, after discharging water in the inner chamber 206 through the water inlet/outlet 212, and flow lines 224 and 228, the air is drawn from the interior of the chamber 202. As a result, the rinsed substrates W are dried. When water in the inner chamber 206 is being discharged, nitrogen gas is simultaneously supplied into the chamber 202 through the flow line 220 and the supply inlet 210 for nitrogen gas. The nitrogen gas prevents dust from adhering to the substrates W.
In the method and the apparatus thereof disclosed in the above-described Japanese Patent Laying-Open No. 3-30330, after washing the substrates W with heated water and rinsing the same with deionized water, water is removed from the surroundings of the substrates by lowering the liquid surface in the inner chamber 206 with the substrates W standing still. However, in the step of discharging water from the inner chamber 206, particles removed from the surface of the substrates W by rinsing and diffused into the liquid are concentrated in the vicinity of the liquid surface. Thus, when the liquid surface is lowered there is a problem that particles will readhere to the surfaces of the substrates W when the liquid surface is lowered on the substrates W that are still standing.
It is also pointed out that the above-described conventional technique has other problems. That is, chamber 202, formed of an anticorrosive material, has an insulating structure. The deionized water, having a large electrical resistance value, is electrically insulated. Therefore, much static electricity is generated in the chamber 202 during the flow of the deionized water. Because of the static electricity, a lot of particles adhere to the surface of the substrates W, for example, a silicon wafer in the chamber 202.
The apparatus disclosed in the above-described Japanese Patent Laying-Open No. 3-30330 further includes a radiating heater, not shown, arranged in the surroundings of the chamber. After rinsing the substrates with water and discharging the water, and before drying the substrates W under the reduced pressure, the substrates W are heated supplementarily by the radiating heater in order to promote drying of the substrates W. However, since the interior of the chamber 202 is almost evacuated in the step of drying, heat is not supplied to the substrates by conduction even if the substrates are heated, resulting in poor efficiency of drying. Since the substrates are heated by radiation from the outside of the chamber, only a limited number of materials are suitable for constructing the chamber. That is, the chamber must be constructed of a transparent material such as quartz.